Zillow Zestimate can be hit or miss since it uses statistics to calculate the price. Many factors contribute to when and for how much a home sells. Foreclosures, short-sales, seller motivation, buyer financing, quickness of closing and interior condition are a few things that play a huge part in the sale price of a home. I am a real estate agent and I actually found that Zillow often over estimated the value of my listings. I think that this points out why it is good to talk with a real estate professional, even Zillow recommends this, when thinking about buying a place.

It's good if you want a general ballpark -- but you shouldn't use it for figuring out what to offer (or what to price for sale). It isn't that close an estimate. If you want to know generally "is this house in the 300s or is it in the 400s" then it's a fine tool. I like it better, when thinking about prices, to sort by recently sold -- I can see what prices are really doing in a given neighborhood.

I caution clients not to pay any attention to Zillow estimates at all. For instance, when I asked for the estimate on my own house, it gave me a price that is well below the assessed value and nowhere near its actual market value. Zillow doesn't have knowledge as to the condition of your home. Often the data is draws from is inaccurate. And more importantly, Zillow doesn't take your location into account, which any Realtor will tell you is the deciding factor in determining the most likely fair market value of your property.

Pricing a property for sale is part science and part art. I wouldn't attempt to put a market value on your home without visting and touring the property. But that's what Zillow attempts to do. It's highly inaccurate and I would suggest, as others here have, that you speak to an experienced Realtor in your area.

PART ONE:As a “real estate professional”, Ms. Tobin has another poorly written (misspellings) and inaccurate post (data). As a licensed real estate managing broker, I will tell you flat out, there is no longer any relationship to what the assessed value of a home is and the listing price, let alone the eventual sales price.

So why even mention it?

Way back in the dark ages there used to be a relationship, but those days are decades gone by. The assessment is done by the town or city and there are variables to determine the number. Assessments aren’t done every year or for 100% valuation (depending on the town), let alone the town assessor going into the home in question on an annual basis and/or checking to see that any improvements/additions were done to code, permits pulled and signed off on by the town inspector – “finalized.”

Secondly, what real estate agents use to determine the market value of your home is also inaccurate, as our “comps” – our numbers - are not 100% accurate.

Why? Why not?

Our MLS (from where our computer pulls our “comp” information for us based upon the criteria we input) only publishes homes sales reported by a real estate agent and member of the local MLS. Many sales are not sold by a real estate agent, such as private sales, foreclosures, “for sale by owner”, etc.Which is why monthly, quarterly and annual housing numbers are never in synch with sites that track housing sales sold by every method, such as the Warren Group in your area.

The housing numbers published by the real estate associations of every State are always more positive than the housing numbers from these other public/private organizations, due to this discrepancy.

What is happening much more now that during the housing bubble (not that it didn’t happen then, but less often as homes sold quickly and over asking price in many instances) is that agents are often low balling and “selectively using comps” to try and get the seller to list their home for a low price so that they can move the home as quickly, as cheaply and in the least amount of time so that we can get our commission check and get paid.

We are salespeople on straight commission, with no salary and no company paid expenses. We are not social workers or paid by the hour whether we sell something or not.

Some agents are fantastic and many others have a different view of customer service and of the selling profession. Just as it with buying any expensive item, housing is very much “buyer beware”.

At least in California and in many other States, we are “full disclosure” States. MA; unfortunately; isn’t one of them. Do your own research, speak to as many people as possible and take your time. Buying a home is a very expensive, emotional proposition and it is loaded with a lot of arcane language, all designed to throw a buyer or seller off guard.

PART TWO: The information reported in the public record is often wrong. Before you put your home on the market, find out what the public record reports on the characteristics of your home and try to correct any mistakes that could work against a sale.

In California and in every State, properties are reassessed for property taxes based on renovations and additions done legally, with permits. Often, the local assessor's office will update its record but many times that information doesn't get into the public record that is accessible by real estate agents, buyers and appraisers.

In one case, a couple had purchased a vacant lot and architectural plans from the previous owner who couldn't afford to build. The couple then added more than 1,000 square feet to the plans and built a bigger house.The public record showed a 3,600-square-foot house, which was the size of the house that was originally planned.

The Certificate of Occupancy (COD) issued by the City of Oakland Planning Department reflected the larger 4,800-square-foot house that was built. Armed with this documentation, the appraiser had no problem appraising the property for the purchase price.

However, it took a well skilled agent to get this information into the hands of the appraiser and if he didn’t have it at the time of his appraisal, it would have come in too low.

Sometimes when an addition is made to a home, the public record is not amended to include the additional square footage. In Alameda County, Calif., a seller can visit the Assessor's Office and ask for a copy of the Property Characteristics Report on their home. If it's not accurate, the seller can request that changes be made.

Mistakes in the public record aren't confined to livable square feet. The public record also includes information about such things as the number of total rooms, the number of bedrooms, bathrooms and whether or not there is a garage.

It can take months for changes to show up in the public record, so start working on this early, REGARDLESS of which town, county or State you live in.

I have a network of fellow brokers I speak with and/or email on a weekly - sometimes daily - basis, from around the country, including the Boston, Cape Cod and the North Shore area. Whatever I've written and whatever examples I've used, also apply to you.

I recentley went onto zillow to look at the house My parents owned and then turned it over to me and my late husband...The statistics were incorrect...first off...The year built was not correct, amount of bedrooms was incorrect and did not add in-law apartment to value...A five bedroom home with 3.5 baths including an in-law quarters is pretty important to me...certain things were NOT included?That entire home was re-contructed in 1984, yet there is no mention of this in their information, instead it gives only the year the original house was built..1948?? I would say they are incorrect on far too many issues to go by them at all...

Hazel1222, you mentioned assessments. This is what I don't get. Assessments in Mass are done two years out. So your property today is much lower than the assessment done for 2011. Case in point, an assessment for 2011 (ex: 350k) is based on data for 2009. Meaning your home was worth roughly 350k in 2009 not 2011. The market has been declining for the past two years so you would have to factor those percentages in. Deduct 15% for each year and you are looking at a figure that is about $254k. We are talking about a 100k price difference. I see this all day long. A lot of realtors price homes close to the Zestimate which is usually based pretty tightly to assessments, so homeowners are way above what should be their target price. It's a flawed system which results in homes sitting on the market for a VERY LONG TIME.

Zillow: Everybody knows better than to trust it 100%, but everybody flocks to Zillow and freaks out by the quoted Zestimates.

In Massachusetts, I've noticed the following problem with Zillow:

/> Zillow fails to recognize that antique or 1700's / 1800's era homes often sell for a premium compared to similar sized "younger" homes in the same area. (and 1700's / 1800's era homes often contain inaccurate public records i.e. correct date of construction (which could be 5 different dates depending on the number of additions), any and all updates over the last 50-100 yrs (which are often done in secret to avoid permitting red tape and/or tax increases)).

Both inside and outside Mass:

/> Zillow fails to recognize that zip codes are not homogenous like they are in Money Magazine stories (that always claim that the best places to live in the US are suburbs of Indianapolis and Minneapolis).

I think a better question is how close is Zillow to the "fly by" appraisals used by banks when qualifying home equity loan applications.

The best way to buy a house is to start looking way before you're ready to buy. Go to a lot of open houses in the areas where you think you want to live as well as the surrounding areas. You should be able to walk into a house and know what it's worth before you make an offer, at least in my opinion.

When I bought my first condo, I knew it was under priced by about $35,000. When I bought my house, I was able to estimate the asking price after looking in the windows. It's not that hard a skill to develop.

A friend of mine told me, "never buy anything or sell anything unless you know what it should cost".

I agree a 100% with DirtyWater, the only way to really judge the value of a property is to look and look and look at the competition first.

Zestimates are garbage in my opinion. I've bought and sold several properties in the past 5 years. When I was looking to buy and sell a condo in Boston I was totally confused by the fact that the unit I was buying was larger and on a higher floor than others in that same building with higher zestimate values. I understand that Zillow cannot account for the condition of a home, but would expect the software to be able to adjust for square footage in the same location. Yet, 4 years later I've now just put an offer on a single family house in the burbs. I looked at the Zestimate of course and was amazed to see this is still a problem. The house across the street is smaller and has a smaller lot and yet is valued at $50k more. The methods Zillow uses are seriously flawed and I would not rely on that information.

Town assessments, the MLS comparative market analysis and Appraisals are not much better. I've seen five professional appraisal reports in the last 5 years. Every single house was valued at exactly the price to the penny that we had agreed to. I'm a licensed real estate agent with access to MLS (not practicing.... I just sat through the weekend course and took a ridiculously easy test to get my license so I could buy and sell my own properties). I can tell you that the tools used to value properties are highly subject to the picture the person picking the comps wants to portray.

My advice would be to take your time and look around a lot before you purchase a house or list your own house. After seeing a few dozen properties in the area you'll have a really good idea of what the house you want to buy or sell is really worth.

Zillow can be very helpful since it does provide accurate information on places that have sold in the area. However, Zillow has a hard time separating multi family homes from single family homes. For instance Zillow may compare a 4 BR, 2 Bath homes with a 2 unit multi family that has 2, 2 BR units.

Additionally, Zillow does not tae location into consideration. It cannot distinguish between a home in a well landscaped cul-de-sac from a home positioned on a highway. I have also seen Zillow compare homes on the water to the homes across the water, which may be a totally different town/city simply because the measurement across the water is less than 1 mile.

What I suggest to do is when looking to Zillow for a Zestimate research what homes or "comps" they are comparing your home to. You can get a better feel for your value by eliminating homes that do not match your home.

Keep in mind, Zillow is based on statistics. It is designed produce a ballpark estimate for the 100 million or so homes in the U.S. In other words, it's a one-size-fits-all formula, so don't expect perfect results.

Garbage in equals garbage out. Funny how during the bubble, when home prices were rising, Zillow was a good resource. "Hey, Zillow says my home is worth $500K, let's list at that price." Now that home prices are falling, Zillow is suddenly not so reliable.

Zillow is a resource and should be as such along with other resources. It will over estimate some homes, under estimate some and some it will get right. I have a few friends that bought right about the peak of the bubble, and Zillow estimatates the value of their homes about 20% less than they paid, which is probably be close to what they could expect to get if they sold.

I think that for construction in the last five years it is not bad, but it begins to break down as the years pass. Not because of age but because of improvements that Zillow seems to have a hard time adjusting for. Many buyers have made some kind of up grade by the time five years have past and most by ten years. Well, at least it is a starting place.